House lawmakers are poised to vote Thursday on whether to expel state Representative Carlos Henriquez, who is serving six months in jail for assaulting a woman, after a disciplinary panel’s unanimous recommendation Tuesday.

Following a marathon hearing that stretched from early afternoon to night, the House Committee on Ethics called on Henriquez’s colleagues to force the Dorchester Democrat from the chamber.

If he is expelled, it will mark only the second time in a century that the body has taken that extraordinary action.

Henriquez, first elected in 2010, was convicted in January of holding down a woman and punching her in the chest when she refused to have sex with him. He is appealing the conviction, and his attorney has questioned the fairness of his trial, asserting that he was convicted by an all-white jury.

Henriquez, 37, has maintained his innocence and refused calls from top elected officials — from Governor Deval Patrick to Mayor Martin J. Walsh of Boston — to resign.

In a 51-page report made public Tuesday evening, the ethics panel said the representative’s conviction and imprisonment puts him in violation of House Rule 16A.

That rule states that members should make every reasonable effort to avoid “transactions, activities, or obligations which are in substantial conflict with or will substantially impair their independence of judgment.”

Speaking to reporters Tuesday night, state Representative Garrett J. Bradley, a Hingham Democrat and member of the committee, said Henriquez’s incarceration means he is breaking that rule.

He “cannot come to the State House and vote, cannot handle matters within his district, and is severely compromised in his ability to be a representative,” Bradley said.

But Henriquez’s attorney, Stephanie Soriano-Mills, said the committee had acted against her client using a “rule that doesn’t apply,” likening it to fitting “a square peg into a round hole.”

“The allegations, as they were, have been around for 18 months,” she said. “The House knew about them. Carlos has had a stellar record. He has voted. He has passed legislation. He has filed bills on behalf of his community. He has done everything he should do as a legislator.”

Bradley also said the committee reviewed photographs of Henriquez’s victim that showed “very damaging black and blue marks on her torso and on her arms.”

After Henriquez was convicted of two misdemeanor counts of assault and battery on Jan. 15, a Cambridge District Court judge sentenced him to 2½ years in the House of Correction and ordered him to serve six months of the sentence.

In remarks to the committee, attached to the report, Henriquez reiterated that he is innocent and called assault and battery against a woman “a cowardly and shameful act for which I am embarrassed to even be associated” with.

The Ethics Committee’s recommendation capped a day of whispered rumors and spectacle. Until a report is issued, the panel’s deliberations are secret, and members are forbidden to speak about them.

Henriquez was seen entering a hearing room on the first floor of the State House at about 1:30 p.m. For the next seven hours, about a dozen journalists stood vigil, watching a door to the room.

At 9 p.m., he exited in handcuffs, surrounded by law enforcement officials. He showed no emotion and did not respond to reporters’ questions as he entered an elevator.

On Monday, the House set ground rules for a possible vote to discipline Henriquez, approving a procedural order that also allows Henriquez to address his colleagues before they pass judgment. The rules require a simple majority of members who are present and voting to expel him, after a quorum is present.

After the Ethics Committee’s report, House Speaker Robert A. DeLeo said in a press release that he would vote to kick out Henriquez.

If he is expelled, Henriquez has no right of reconsideration or appeal.

House minority leader Bradley Jones, Republican of North Reading, said he expected the House would cast “a pretty strong, if not overwhelming vote to accept the report.”

“Will it be unanimous? I don’t know about that,” Jones said. “I don’t look forward to going in on Thursday. I don’t consider this as anything other than a sad day for the institution.”

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